Department of Plant Biology, Carnegie Institution of Washington, 94305, Stanford, CA, USA.
Planta. 1987 Apr;170(4):489-504. doi: 10.1007/BF00402983.
Photon yields of oxygen evolution at saturating CO2 were determined for 44 species of vascular plants, representing widely diverse taxa, habitats, life forms and growth conditions. The photonyield values on the basis of absorbed light (φ (a)) were remarkably constant among plants possessing the same pathway of photosynthetic CO2 fixation, provided the plants had not been subjected to environmental stress. The mean φ (a) value ±SE for 37 C3 species was 0.106±0.001 O2·photon(-1). The five C4 species exhibited lower photon yields and greater variation than the C3 species (φ (a)=0.0692±0.004). The φ (a) values for the two Crassulaceanacid-metabolism species were similar to those of C3 species. Leaf chlorophyll content had little influence on φ (a) over the range found in normal, healthy leaves. Chlorophyll fluorescence characteristics at 77 K were determined for the same leaves as used for the photon-yield measurements. Considerable variation in fluorescence emission both at 692 nm and at 734 nm, was found 1) among the different species; 2) between the upper and lower surfaces of the same leaves; and 3) between sun and shade leaves of the same species. By contrast, the ratio of variable to maximum fluorescence emission at 692 nm (Fv/FM, 692) remained remarkably constant (The mean value for the C3 species was 0.832±0.004). High-light treatments of shade leaves resulted in a reduction in both φ (a) and the Fv/FM, 692 ratio. The extent of the reductions increased with time of exposure to bright light. A linear relationship was obtained when φ (a) was plotted against Fv/FM, 692. The results show that determinations of the photon yield of O2 evolution and the Fv/FM, 692 ratio can serve as excellent quantitative measures of photoinhibition of overall photosynthetic energy-conversion system and of photochemistry of photosystem II, respectively. This is especially valuable in field work where it is often impossible to obtain appropriate controls.
在饱和 CO2 条件下，测定了 44 种维管束植物的氧气演化光子产量，这些植物代表了广泛的生物多样性、生境、生活形式和生长条件。在具有相同光合作用 CO2 固定途径的植物中，如果植物没有受到环境胁迫，基于吸收光的光子产量（φ(a)）值在植物之间非常稳定。37 种 C3 物种的平均φ(a)值±SE 为 0.106±0.001 O2·光子(-1)。五种 C4 物种的光子产量较低，且比 C3 物种变异更大（φ(a)=0.0692±0.004）。两种景天酸代谢物种的φ(a)值与 C3 物种相似。在正常健康叶片中发现的范围内，叶片叶绿素含量对φ(a)的影响很小。为了进行光子产量测量，还测定了相同叶片的 77 K 叶绿素荧光特性。在不同物种之间；2）在同一叶片的上下表面之间；以及 3）在同一物种的阳光和阴凉叶片之间，发现了荧光发射的相当大的变异 1）。相比之下，692nm 处的可变荧光与最大荧光发射之比（Fv/FM，692）保持相当稳定（C3 物种的平均值为 0.832±0.004）。阴凉叶片的高光处理导致φ(a)和 Fv/FM，692 比值降低。随着暴露在明亮光线下的时间的增加，降低的程度增加。当将φ(a)绘制为 Fv/FM，692 时，获得了线性关系。结果表明，O2 演化光子产量和 Fv/FM，692 比值的测定可以分别作为整体光合作用能量转换系统和光系统 II 光化学光抑制的极好的定量测量。这在现场工作中特别有价值，在现场工作中通常不可能获得适当的对照。
